Flat tubular bags of the described type are known. The bag surfaces of such bags, which lie congruent on one another, are simply folded at the edges extending parallel to the longitudinal seam, thus achieving the flat bag shape. Side-fold bags are also known.
Also tubular bagging machines for the manufacture of such bags are known.
The known flat, filled tubular bags of the described type have the disadvantage that they are not suited to stand erect for presentation in a tray since they have the tendency to fold and fall over. The folding occurs mainly parallel to the cross seams of the bags standing on their bottom-side cross seam, and is particularly prevalent when a row to be filled with bags arranged one behind the other in a tray is not complete so that the row to be filled is not supported by a boundary of the tray.
Tubular bagging machines with a side-fold producer are known, in which a side fold in a film tube is produced by a movable side-fold bar. Also side-fold bars movable toward one another are known, which create two oppositely lying side folds in the film tube. Such tubular bagging machines create tubular bags with a side fold or with two side folds. The tubular bags are welded together at the top and at the bottom by cross seams. The side folds are merely welded into the cross seams.
The disadvantage of the known tubular bagging machines with a side-fold bar or with two side-fold bars is that the created tubular bags while having greater relatively stability against deformations because of the side folds, however, still lack a greater stability required for many areas of use.
A tubular bagging machine with an asymmetrical forming shoulder is known from the U.S. Pat. No. 4,194,438. The forming shoulder is used to shift the longitudinal seam of a tubular bag with a rectangular cross section to the edge of the tubular bag in order to avoid a longitudinal seam extending centrally on a side surface of the tubular bag, and in order to be able to utilize, in this manner, the surface of the side surface efficiently for product information.
U.S. Pat. No. 3,426,499 also discloses an arrangement for shifting the longitudinal seam into a corner of a square-shaped bag.
The devices of the U.S. Pat. No. 4,194,438 and of U.S. Pat. No. 3,426,499 have the disadvantage that their longitudinal seams hardly prevent a folding of the corners of the tubular bag.